Development and Growth
Although vellus hair is already present in the area in childhood, the term chest hair is generally restricted to the terminal hair that develops as an effect of rising levels of androgens (primarily testosterone and its derivatives) due to puberty. Different from the head hair it is therefore a secondary sexual characteristic. Men tend to be covered with far more terminal hair, particularly on the chest, the abdomen and the face.
The development of chest hair begins normally during late puberty, usually between the ages of 15 and 18. It can also start later, between the age of 20 and 30, so that many men in their twenties have not yet reached their full chest hair development. The growth continues subsequently. In older adult years androgens cause thickening of the hair.
Read more about this topic: Chest Hair
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